Rename Desktop->RootWindow.

ui/aura/desktop_observer.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef UI_AURA_DESKTOP_OBSERVER_H_
-#define UI_AURA_DESKTOP_OBSERVER_H_
-#pragma once
-
-#include "ui/aura/aura_export.h"
-
-namespace gfx {
-class Size;
-}
-
-namespace aura {
-
-class Window;
-
-class AURA_EXPORT DesktopObserver {
- public:
-  // Invoked after the desktop is resized.
-  virtual void OnDesktopResized(const gfx::Size& new_size) {}
-
-  // Invoked when a new window is initialized.
-  virtual void OnWindowInitialized(Window* window) {}
-
-  // Invoked when the active window is changed. |active| may be NULL if there is
-  // not active window.
-  virtual void OnActiveWindowChanged(Window* active) {}
-
- protected:
-  virtual ~DesktopObserver() {}
-};
-
-}  // namespace aura
-
-#endif  // UI_AURA_DESKTOP_OBSERVER_H_